Field of the Invention
The present invention relates to an image forming apparatus having a detachable cartridge.
Description of the Related Art
There has conventionally been known a cartridge system image forming apparatus that uses electrophotographic image forming process, in which a photosensitive drum and a developing unit accommodating a developing roller that acts on the photosensitive drum and a developing agent (toner) are integrally formed.
There is also known a developing cartridge type system, that is configured just of a developing unit, separately from the photosensitive drum. According to these cartridge systems, maintenance of the image forming apparatus can be performed by the user him/herself, without having to depend on a field engineer for service.
Accordingly, these cartridge systems are in widespread use in electrophotographic image forming apparatuses.
There also is known a technology configured where a supporting member detachably supporting a cartridge is provided, and exchanging work of cartridges can be performed by extracting the supporting member from within the main unit of the electrophotographic image forming apparatus to a predetermined position. According to this technology, the user can easily perform replacement of developing agent.
Japanese Patent Laid-Open No. 2009-157135 describes providing an image exposing member, that exposes the surface of the photosensitive drum and forms an electrostatic latent image, on a supporting member detachably supporting a cartridge. This proposes a technology to realize both reduction in retracting space of the image exposing member and ease of work of cartridge replacement by the user.
However, in the technology in Japanese Patent Laid-Open No. 2009-157135, if the user erroneously attempts to mount a cartridge in a supporting member at a position different from the correct mounting position, there is a risk of the image exposing member and a frame making up the cartridge colliding. This can damage the image exposing member, and obstruct image forming.
Also, in the technology in Japanese Patent Laid-Open No. 2009-157135, the user mounts the cartridge into the supporting member by sliding a rotating shaft of the cartridge along a guide groove within the supporting member. In a case where the user performs an action of rotating the cartridge on the rotating shaft, there is a risk of the cartridge and image exposing member colliding.
It has been found to be advantageous to avoid collision between an image exposing member and cartridge when mounting the cartridge within a supporting member having the image exposing member.